Refractory materials, such as borides, carbides, nitrides and silicides of the transition metals, as well as silicon carbide and trisilicon tetranitride find utilization in a wide variety of industrial applications because of their hardness, chemical inertness, and high melting point characteristics. They are used as abrasives, refractory materials, cutting tools, in high speed machinery applications, and for compacting by powder metallurgical techniques. Their unique physical characteristics would make them especially useful for a number of jet engine applications except for their inherent brittleness. These normally high temperature melting compounds, with their high hardness and strength, are extremely brittle. This severely limits their usefulness for jet engine applications which could otherwise take advantage of their unique properties. It would seem, therefore, that these materials should make excellent candidates as structural materials in the fabrication of jet engine components, such as turbine blades. Unfortunately, these refractory compounds exhibit a high degree of brittleness which severely limits their usefulness in the manufacture of certain machine components such as the hereinbefore mentioned turbine blades.
In accordance with this invention, however, it has been found that the problem of brittleness, which severely limits the utilization of carbides, borides and nitrides for certain industrial applications, can be overcome by effecting the macroscopic deformation of these very brittle refractory crystals through a unique pressure technique conducted at room temperature. The deformation occurs through an elastic-plastic mechanism on the crystallographic planes or slip planes of the hexagonal crystal structure. The resultant increase in ductility or workability of these high temperature materials at room temperature provides an unexpected improvement in their utility for various jet engine applications, such as in the fabrication of turbine blades and other turbine engine components. Their use as turbine engine components allows for high temperature operation resulting in improved fuel efficiency for jet engines. They also find utility in the manufacture of high speed machine lathe tools and high speed drills.
An additional benefit resulting from the present invention is the unexpected increase in electrical conductivity exhibited by the deformed crystals of the invention. This high conductivity borders on superconductivity at room temperature. At the present time, all known superconductors are only effective at cryogenic temperatures which are difficult to attain and maintain, thus limiting their practical use. However, with this invention the usefullness of refractory carbides, borides and nitrides can be extended to a marked degree--not only for jet engine and high speed tool applications, but also for various electronic applications requiring highly conductive materials capable of operating within an elevated temperature environment of high mechanical stress. For example, very high current switches often require structural materials having the very unique and extraordinary properties exhibited by the deformed crystals of this invention. In high speed computers, very fast switching devices are needed that can overcome the large resistance created when changing from a semiconductor range to a superconductive range. The present invention provides the means for fabricating fast switching devices that overcome the resistance problem because the superconductivity of the crystals of this invention occurs at room temperature.